[Travassosius rufus (Trichostrongylidae)--new for Poland nematode of beavers and comments about helminthfauna of these animals].

Two females of beaver from north-east Poland were necropsied. Moreover, 15 samples of feaces were examinated. Both necropsied beavers were infected with 46 and 362 specimens of trematode Stichorchis subtriquetrus (RUDOLPHI 1814). In stomach of one beaver were found 2800 specimens of nematode Travassosius rufus Khalil, 1922. It was the first registration of this species in Poland. Coproscopical examination showed eggs of S. subtriquetrus in all 15 fecal samples and eggs T. rufus in 5 samples.